Evaluating fairness in devices under test

ABSTRACT

Pre-silicon fairness evaluation to detect fairness issues pre-silicon. Drivers drive a plurality of commands on one or more interfaces of a device under test to test the device under test. State associated with the device under test is checked. Based on the state, a determination is made as to whether the drivers are to continue driving commands against the device under test. Based on determining that the drivers are to continue driving the commands, a further determination is made as to whether a predefined limit has been reached. Based on determining the predefined limit has been reached, ending the test of the device under test in which the test fails.

This application is a continuation of co-pending U.S. Ser. No.14/501,709, entitled “EVALUATING FAIRNESS IN DEVICES UNDER TEST,” filedSep. 30, 2014, which is hereby incorporated herein by reference in itsentirety.

BACKGROUND

One or more aspects relate, in general, to pre-silicon testing, and inparticular, to evaluating fairness during pre-silicon testing of devicesunder test.

During the pre-silicon process, devices are tested in a virtualenvironment with sophisticated simulation, emulation and formalverification tools. In contrast, post-silicon validation tests occur onactual devices running at-speed in commercial, real-world systems.Pre-silicon testing performs various tests to determine functionalcorrectness and/or to assess performance of the devices under testand/or the system that includes such devices.

In assessing performance, one or more criteria are considered, includingfairness. Fairness relates, in general, to whether forward progress isbeing made for traffic (e.g., commands, instructions, and/or other typesof traffic) being driven on interfaces of the device under test.Fairness, and in particular, a lack of fairness, is difficult todiscover in current simulation test environments, since bus functionalmodels, which drive traffic on the interfaces, are quiesced atpre-determined, fixed cycles. This stops new commands from being drivenon the interfaces, allowing outstanding traffic—even if previously notmaking expected forward progress due to a fairness issue—to finishwithin the run out period of the testcase.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages areprovided through the provision of a computer-implemented method ofevaluating fairness in devices under test. The computer-implementedmethod includes, for instance, driving, by a plurality of driversexecuting on one or more processors, a plurality of commands on one ormore interfaces of a device under test to test the device under test;checking state associated with the device under test, wherein the stateis based on status of selected commands driven by the plurality ofdrivers; and determining, based on checking the state, whether theplurality of drivers is to continue driving commands against the deviceunder test, wherein based on the determining indicating the plurality ofdrivers is to continue driving commands, deciding, based on a predefinedlimit, whether the test is to end, and based on deciding the test is toend, ending the test of the device under test in which the test fails.

Computer program products and systems relating to one or more aspectsare also described and may be claimed herein. Further, services relatingto one or more aspects are also described and may be claimed herein.

Additional features and advantages are realized through the techniquesdescribed herein. Other embodiments and aspects are described in detailherein and are considered a part of the claimed aspects.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects are particularly pointed out and distinctly claimedas examples in the claims at the conclusion of the specification. Theforegoing and objects, features, and advantages of one or more aspectsare apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts one embodiment of a computing environment to incorporateand use one or more aspects of a fairness evaluation technique;

FIG. 2A depicts another embodiment of a computing environment toincorporate and use one or more aspects of a fairness evaluationtechnique;

FIG. 2B depicts further details of the memory of FIG. 2A;

FIG. 3A depicts one example of a device under test with a plurality ofdrivers driving traffic on interfaces of the device under test;

FIG. 3B depicts one example of a global driver control to be used tomanage the plurality of drivers of FIG. 3A;

FIG. 4 depicts one embodiment of logic to evaluate fairness in a deviceunder test, in accordance with one or more aspects;

FIGS. 5A-5B also depict one embodiment of logic to evaluate fairness ina device under test, in accordance with one or more aspects;

FIG. 6 depicts one embodiment of a computer program productincorporating one or more aspects;

FIG. 7 depicts one embodiment of a cloud computing node;

FIG. 8 depicts one embodiment of a cloud computing environment; and

FIG. 9 depicts one example of abstraction model layers.

DETAILED DESCRIPTION

In accordance with one or more aspects, a pre-silicon fairnessevaluation facility is provided and used to detect fairness issuespre-silicon. The ability to discover such issues pre-silicon saves testfloor debug time and the need to correct such problems post-silicon.This results in higher quality designs at a lower cost and savings tothe production schedule.

Fairness issues include, but are not limited to, livelock, starvation,priority and/or other fairness issues. Livelock occurs when more thanone command takes action causing neither to make forward progress.(Commands and instructions are used interchangeably herein unlessotherwise noted either explicitly or implicitly.) Starvation is when acommand is perpetually denied resources, and therefore, does not makeforward progress.

One embodiment of a computing environment to incorporate and use one ormore aspects of a fairness evaluation facility is described withreference to FIG. 1. Referring to FIG. 1, in one example, a computingenvironment 100 is based on the Power Architecture, offered byInternational Business Machines (IBM®) Corporation, Armonk, N.Y., andincludes, for instance, a pSeries or System p server.

IBM, POWER, SYSTEM P, and AIX, Z/ARCHITECTURE, POWER ARCHITECTURE andPOWERPC (referenced below) are registered trademarks of InternationalBusiness Machines Corporation, Armonk, N.Y. Other names used herein maybe registered trademarks, trademarks or product names of InternationalBusiness Machines Corporation or other companies.

As one example, computing environment 100 includes a processor (e.g., acentral processing unit—CPU) 102 communicatively coupled to memory 104and an input/output (I/O) subsystem 106. I/O subsystem 106 is furthercommunicatively coupled to external I/O devices 108 that may include,for example, data input devices, sensors and/or output devices, such asdisplays.

Memory 104 includes, for instance, one or more caches 110, at least onecontrol utility 112, such as an operating system (e.g., AIX, offered byInternational Business Machines Corporation, Armonk, N.Y.), and one ormore aspects of a fairness evaluation facility 114 to be executed by theprocessor to test devices under test.

Another embodiment of a computing environment to incorporate and use oneor more aspects of a fairness evaluation facility is described withreference to FIG. 2A. In this example, a computing environment 200includes, for instance, a native central processing unit (CPU) 202, amemory 204, and one or more input/output devices and/or interfaces 206coupled to one another via, for example, one or more buses 208 and/orother connections. As examples, computing environment 200 may include aPowerPC processor or a Power Systems server offered by InternationalBusiness Machines Corporation, Armonk, N.Y.; an HP Superdome with IntelItanium II processors offered by Hewlett Packard Co., Palo Alto, Calif.;and/or other machines based on architectures offered by InternationalBusiness Machines Corporation, Hewlett Packard, Intel, Oracle, orothers.

Native central processing unit 202 includes one or more native registers210, such as one or more general purpose registers and/or one or morespecial purpose registers used during processing within the environmentthat include information that represents the state of the environment atany particular point in time.

Moreover, native central processing unit 202 executes instructions andcode that are stored in memory 204. In one particular example, thecentral processing unit executes emulator code 212 stored in memory 204.This code enables the computing environment configured in onearchitecture to emulate one or more other architectures. For instance,emulator code 212 allows machines based on architectures other than thez/Architecture, such as PowerPC processors, Power Systems servers, HPSuperdome servers or others, to emulate the z/Architecture and toexecute software and instructions developed based on the z/Architecture,or allows machines based on architectures other than the PowerArchitecture, such as HP Superdome Servers or others, to emulate thePower Architecture and to execute software and instructions developedbased on the Power Architecture.

Further details relating to emulator code 212 are described withreference to FIG. 2B. Guest instructions 250 stored in memory 204comprise software instructions (e.g., correlating to machineinstructions) that were developed to be executed in an architectureother than that of native CPU 202. For example, guest instructions 250may have been designed to execute on a Power Architecture (orz/Architecture) processor 102, but instead, are being emulated on nativeCPU 202, which may be, for example, an Intel Itanium II processor. Inone example, emulator code 212 includes an instruction fetching routine252 to obtain one or more guest instructions 250 from memory 204, and tooptionally provide local buffering for the instructions obtained. Italso includes an instruction translation routine 254 to determine thetype of guest instruction that has been obtained and to translate theguest instruction into one or more corresponding native instructions256. This translation includes, for instance, identifying the functionto be performed by the guest instruction and choosing the nativeinstruction(s) to perform that function.

Further, emulator code 212 includes an emulation control routine 260 tocause the native instructions to be executed. Emulation control routine260 may cause native CPU 202 to execute a routine of native instructionsthat emulate one or more previously obtained guest instructions and, atthe conclusion of such execution, return control to the instructionfetch routine to emulate the obtaining of the next guest instruction ora group of guest instructions. Execution of the native instructions 256may include loading data into a register from memory 204; storing databack to memory from a register; or performing some type of arithmetic orlogic operation, as determined by the translation routine. In oneexample, the guest instructions that are fetched and translated intonative instructions may be instructions of the fairness evaluationfacility used to test the devices under test.

Each routine is, for instance, implemented in software, which is storedin memory and executed by native central processing unit 202. In otherexamples, one or more of the routines or operations are implemented infirmware, hardware, software or some combination thereof. The registersof the emulated processor may be emulated using registers 210 of thenative CPU or by using locations in memory 204. In embodiments, guestinstructions 250, native instructions 256 and emulator code 212 mayreside in the same memory or may be disbursed among different memorydevices.

As used herein, firmware includes, e.g., the microcode, millicode and/ormacrocode of the processor. It includes, for instance, thehardware-level instructions and/or data structures used inimplementation of higher level machine code. In one embodiment, itincludes, for instance, proprietary code that is typically delivered asmicrocode that includes trusted software or microcode specific to theunderlying hardware and controls operating system access to the systemhardware.

The computing environments described above are only examples ofcomputing environments that can be used. Other environments, includingbut not limited to, other non-partitioned environments, partitionedenvironments, and/or other emulated environments, may be used;embodiments are not limited to any one environment or to any particulararchitecture or system.

Fairness evaluation logic executed by one or more processors of acomputing environment is used to test a device under test. Inparticular, in this example, the fairness evaluation logic is used toevaluate fairness for the device under test. The device under test maybe of many designs, but in the example described herein, it is a cache,such as an L3 cache, design. However, this is only one example of adesign that may be tested pre-silicon.

Referring to FIG. 3A, in one embodiment, traffic (e.g., commands,instructions, etc.) is driven on interfaces of a device under test 300,such as a cache design, by a plurality of drivers 302. As used herein, adriver is any entity used to drive traffic on the device under test. Inone embodiment, the driver drives traffic on the interfaces of thedevice under test, and therefore, may be referred to as an interfacedriver. A particular example of a driver is a bus functional model,which may be defined as tasks in, for instance, hardware descriptionlanguages. The drivers may be of different types. For instance, in thisexample, the drivers include processing cores 302 a, fabric drivers 302b, memory drivers 302 c, and input/output (I/O) drivers 302 d, each ofwhich executes on a processor and drives traffic on the device undertest, as appropriate for the type of driver.

Conventionally, each driver drives traffic on the device under testuntil a fixed quiesce time (e.g., 50,000 cycles), which is predefinedprior to a start of the test, is reached. When the fixed quiesce time isreached, the driver stops driving traffic. However, by stopping thetraffic at fixed points, a fairness issue may be masked, sinceoutstanding traffic—even if previously not making expected forwardprogress due to a fairness issue—is allowed to finish. Thus, inaccordance with one or more aspects, fairness is evaluated based on astate of the driver, instead of a fixed quiesce point, such as a fixedcycle count. In one embodiment, a global driver control facilitates inevaluating fairness based on the driver state.

Referring to FIG. 3B, in one embodiment, a global driver control 304executing on a processor within the computing environment is used, inone or more aspects, in controlling the individual instances of drivers302. The global driver control maintains state information associatedwith the drivers, such as, for instance, status relating to the trafficdriven by the drivers, and this information is used by the fairnessevaluation logic to control the driving of traffic by the drivers, andthus, discover fairness problems in pre-silicon designs under test.

One embodiment of fairness evaluation logic used to test a device undertest is described with reference to FIG. 4. In one example, this logicis performed by each driver to test the device under test.

Referring to FIG. 4, initially, a simulation interface driver, such as abus functional model, drives commands on its interface of the deviceunder test, STEP 400. A determination is made, at preselected intervals,whether a pre-quiesce limit associated with the driver has been reached,INQUIRY 402. The pre-quiesce limit is a parameter set by the user forthe driver to be used to determine whether state for the driver is to becollected. The pre-quiesce limit is, for instance, based on processingcycles, but could be based on other criteria. In one particular example,it is set at 30,000 cycles; however, other criteria may be used.

If the driver pre-quiesce limit has not been reached, INQUIRY 402, thenthe driver continues to drive commands, STEP 400. However, if the driverpre-quiesce limit has been reached, INQUIRY 402, then the driver takes asnapshot of one or more selected commands that have been driven on thedevice under test by the driver, STEP 404. In one example, the one ormore selected commands include the oldest outstanding command that hasbeen driven; i.e., the longest executing command with reference to aparameter, such as time, cycle count, etc. It is the longest executingcommand or oldest outstanding command as compared to other commandsdriven by the driver and currently executing. However, in otherembodiments, other commands may be selected, such as all the commands orsome other subset of commands, etc. This snapshot includes, forinstance, a sequence identifier of the command, a command code pointtype (e.g., read-only fetch), address of the command, and the timepresented on the interface.

The driver continues to drive commands on the interface, STEP 406, anddetermines, at predefined intervals, whether the selected command (e.g.,the longest executing command) has reached a predefined point (e.g.,completion), INQUIRY 408. If the selected command has not reached thepredefined point, then the driver continues to drive commands on theinterface, STEP 406. However, if the driver determines that the selectedcommand has reached the predefined point, then the driver posts to theglobal driver control that the selected command for this driver hasreached the predefined point, STEP 410. That is, the driver providesstatus of the selected command. The driver continues to drive commandson the interface, STEP 412.

The driver inquires, at preselected intervals, as to whether the globaldriver control has indicated that all of the drivers driving trafficagainst the device under test have indicated that their selectedcommands (e.g., each driver's longest executing command) have reachedthe predefined point (e.g., completion), INQUIRY 414. That is, thedriver checks state of the device under test. If the global drivercontrol has not indicated that all of the drivers have posted that theirselected commands have reached the predefined point, then a furtherdetermination is made as to whether a predefined limit (e.g., a hangtime) has been reached, INQUIRY 416. The predefined limit is set, forinstance, by the user for each driver at the start of the test. Thevalue for the limit may be the same for each driver or different limitsfor one or more drivers. As one example, the limit is set as, forinstance, a number of cycles (e.g., 80,000 cycles); however, otherlimits and other types of limits may be used. Further, in oneembodiment, the predefined limit may be dynamically adjusted or set,during the test, based on the type of commands being executed and/orexecution characteristics of the commands.

If the predefined limit is not reached, then the driver continues todrive commands against the device under test, STEP 412. However, if thepredefined limit is reached, then the test fails indicating a lack offairness in the device under test, STEP 418. In particular, one or morecommands being driven by this particular driver against the device undertest are considered as failed, indicating a lack of fairness (e.g., didnot receive the resources needed for forward progress in an acceptabletime).

Returning to INQUIRY 414, if the driver determines that the globaldriver control has indicated that all of the selected commands havereached the predefined point, then the driver stops driving commands onthe interface, STEP 420. For instance, a global quiesce point (e.g.,quiesce time) is dynamically set by the global driver control duringexecution of the test based on the driver state (e.g., status of theselected commands). The global quiesce point is used by each of thedrivers to stop driving commands on the interfaces being used to testthe device under test. Thus, the test passes, STEP 422. That is, nofairness issue is determined in the device under test.

Described in detail herein is a simulation test environment thatsupports a driver pre-quiesce time, which is set by the user as aparameter for the testcase. In one embodiment, the simulation drivers inthe system capture, e.g., their oldest outstanding command at the driverpre-quiesce time. Further, the test environment supports a global drivercontrol which is used to dynamically determine a driver final quiescetime. Each individual driver in the system posts to the global drivercontrol when, e.g., their oldest outstanding command has completed. Theglobal driver sets the driver final quiesce time when all of theindividual drivers in the system have posted to the global drivercontrol that, e.g., the oldest outstanding command has completed. Eachindividual driver in the system continues to drive traffic on theirrespective interface until the dynamically set driver final quiescetime.

The test environment supports a parameter to set a hang limit for theoldest outstanding commands and fail upon that condition. The parameteris set, per instance of each driver, at the start on the testcase. If adriver instance detects that its oldest outstanding command is stillactive upon reaching this hang limit, the testcase will fail andindicates the failing command.

In one embodiment, the dynamic setting of driver quiesce time across thesystem is based on driver state (e.g., completion of oldest command),rather than based on cycle count. It is dynamically set during executionof the test, rather than predefined and fixed prior to the start of thetest. As indicated, the technique includes dynamically setting thedriver quiesce time globally, for all drivers in the system under test,including drivers of different interface types. A snapshot state ofdrivers is used to influence future input streams. The snapshot state ofone driver influences the quiesce time for all drivers in the system.Drivers are evaluated against each other for fairness even thoughdrivers can represent different traffic. Drivers behave without fixedconstraints of sending fixed predefined numbers of commands and thenstopping, etc.

To further describe, with reference to FIGS. 5A-5B, in one embodiment, aplurality of drivers drive a plurality of commands on one or moreinterfaces of a device under test to test the device under test, STEP500 (FIG. 5A). For instance, each driver drives commands on itsinterface and determines whether a pre-quiesce limit set for the driverhas been reached, STEP 502. If the pre-quiesce limit for the driver hasnot been reached, then the driver continues to drive commands on thedevice under test, STEP 504. However, if the pre-quiesce limit has beenreached, then a snapshot of one or more selected commands is taken, STEP506. In one example, the snapshot is of the oldest outstanding orlongest executing command for the driver. The driver continues drivingcommands, STEP 508.

Further, state associated with the device under test is checked, STEP510. For instance, the state is based on the status of selected commands(e.g., the longest executing commands) driven by the plurality ofdrivers. For example, a check is made as to whether the selectedcommands have reached a predefined point in execution, STEP 512. Thatis, in one example, has the longest executing command for each driverreached completion.

Based on checking this state, a determination is made as to whether theplurality of drivers is to continue driving commands against the deviceunder test, STEP 514 (FIG. 5B). That is, has the global driver controlposted that the longest executing command for each driver has completed.If the drivers are to stop driving commands because all the selectedcommands have reached the predefined point, then the global drivercontrol sets a global quiesce point, STEP 516. This is set dynamically(e.g., during execution of the test) based on status of the longestexecuting commands. The drivers stop driving commands and the testpasses.

However, if the drivers are to continue driving commands, since theglobal driver control has not posted that the selected commands havereached the predefined point, then a further check is made for eachdriver as to whether a predefined limit has been reached, STEP 518. Ifthe predefined limit has been reached, then the test is to end (e.g.,stop driving commands), and the test fails; otherwise, the drivercontinues driving commands.

Described in detail herein is a technique to discover a class ofproblems historically difficult to uncover via pre-silicon randomsimulation, such as livelock, starvation, fairness and priority issues,collectively referred to herein as fairness issues or problems. Suchissues are difficult to discover in current random simulationmethodology due to the way interface drivers are quiesced at apre-determined, fixed cycle. The issues are masked by the fact that newcommands are no longer driven on the interface after a fixed cycle,allowing outstanding traffic—even if previously not making expectedforward progress due to a fairness issue—to finish within the run outperiod of the testcase. However, in accordance with one or more aspects,fairness issues, such as starvation, fairness, livelock and priorityproblems, are discovered pre-silicon, saving test floor debug time and aneed to fix such problems in additional passes of silicon. The result ishigher quality design at a lower cost and savings to schedule.

As will be appreciated by one of average skill in the art, aspects ofembodiments may be embodied as a system, method or computer programproduct. Accordingly, aspects of embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as, for example, a “circuit,” “module” or “system.”Furthermore, aspects of embodiments may take the form of a computerprogram product embodied in one or more computer readable storagedevice(s) having computer readable program code embodied thereon.

One or more of the capabilities of embodiments can be implemented insoftware, firmware, hardware, or some combination thereof. Further, oneor more of the capabilities can be emulated.

Referring to FIG. 6, in one example, a computer program product 600includes, for instance, one or more non-transitory computer readablestorage media 602 to store computer readable program code means, logicand/or instructions 504 thereon to provide and facilitate one or moreembodiments.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

In addition to the above, one or more aspects may be provided, offered,deployed, managed, serviced, etc. by a service provider who offersmanagement of customer environments. For instance, the service providercan create, maintain, support, etc. computer code and/or a computerinfrastructure that performs one or more aspects for one or morecustomers. In return, the service provider may receive payment from thecustomer under a subscription and/or fee agreement, as examples.Additionally or alternatively, the service provider may receive paymentfrom the sale of advertising content to one or more third parties.

In one aspect, an application may be deployed for performing one or moreembodiments. As one example, the deploying of an application comprisesproviding computer infrastructure operable to perform one or moreembodiments.

As a further aspect, a computing infrastructure may be deployedcomprising integrating computer readable code into a computing system,in which the code in combination with the computing system is capable ofperforming one or more embodiments.

As yet a further aspect, a process for integrating computinginfrastructure comprising integrating computer readable code into acomputer system may be provided. The computer system comprises acomputer readable medium, in which the computer medium comprises one ormore embodiments. The code in combination with the computer system iscapable of performing one or more embodiments.

Although various embodiments are described above, these are onlyexamples. For example, computing environments of other architectures canbe used to incorporate and use one or more embodiments. Further,different states may be used, and the drivers may be of different types.Many variations are possible.

Further, other types of computing environments can benefit and be used.As an example, a data processing system suitable for storing and/orexecuting program code is usable that includes at least two processorscoupled directly or indirectly to memory elements through a system bus.The memory elements include, for instance, local memory employed duringactual execution of the program code, bulk storage, and cache memorywhich provide temporary storage of at least some program code in orderto reduce the number of times code must be retrieved from bulk storageduring execution.

Input/Output or I/O devices (including, but not limited to, keyboards,displays, pointing devices, DASD, tape, CDs, DVDs, thumb drives andother memory media, etc.) can be coupled to the system either directlyor through intervening I/O controllers. Network adapters may also becoupled to the system to enable the data processing system to becomecoupled to other data processing systems or remote printers or storagedevices through intervening private or public networks. Modems, cablemodems, and Ethernet cards are just a few of the available types ofnetwork adapters.

In a further embodiment, one or more aspects relate to cloud computing.It is understood in advance that although this disclosure includes adetailed description on cloud computing, implementation of the teachingsrecited herein are not limited to a cloud computing environment. Rather,embodiments of the present invention are capable of being implemented inconjunction with any other type of computing environment now known orlater developed.

Cloud computing is a model of service delivery for enabling convenient,on-demand network access to a shared pool of configurable computingresources (e.g. networks, network bandwidth, servers, processing,memory, storage, applications, virtual machines, and services) that canbe rapidly provisioned and released with minimal management effort orinteraction with a provider of the service. This cloud model may includeat least five characteristics, at least three service models, and atleast four deployment models.

Characteristics are as follows:

On-demand self-service: a cloud consumer can unilaterally provisioncomputing capabilities, such as server time and network storage, asneeded automatically without requiring human interaction with theservice's provider.

Broad network access: capabilities are available over a network andaccessed through standard mechanisms that promote use by heterogeneousthin or thick client platforms (e.g., mobile phones, laptops, and PDAs).

Resource pooling: the provider's computing resources are pooled to servemultiple consumers using a multi-tenant model, with different physicaland virtual resources dynamically assigned and reassigned according todemand. There is a sense of location independence in that the consumergenerally has no control or knowledge over the exact location of theprovided resources but may be able to specify location at a higher levelof abstraction (e.g., country, state, or datacenter).

Rapid elasticity: capabilities can be rapidly and elasticallyprovisioned, in some cases automatically, to quickly scale out andrapidly released to quickly scale in. To the consumer, the capabilitiesavailable for provisioning often appear to be unlimited and can bepurchased in any quantity at any time.

Measured service: cloud systems automatically control and optimizeresource use by leveraging a metering capability at some level ofabstraction appropriate to the type of service (e.g., storage,processing, bandwidth, and active user accounts). Resource usage can bemonitored, controlled, and reported providing transparency for both theprovider and consumer of the utilized service.

Service Models are as follows:

Software as a Service (SaaS): the capability provided to the consumer isto use the provider's applications running on a cloud infrastructure.The applications are accessible from various client devices through athin client interface such as a web browser (e.g., web-based email). Theconsumer does not manage or control the underlying cloud infrastructureincluding network, servers, operating systems, storage, or evenindividual application capabilities, with the possible exception oflimited user-specific application configuration settings.

Platform as a Service (PaaS): the capability provided to the consumer isto deploy onto the cloud infrastructure consumer-created or acquiredapplications created using programming languages and tools supported bythe provider. The consumer does not manage or control the underlyingcloud infrastructure including networks, servers, operating systems, orstorage, but has control over the deployed applications and possiblyapplication hosting environment configurations.

Infrastructure as a Service (IaaS): the capability provided to theconsumer is to provision processing, storage, networks, and otherfundamental computing resources where the consumer is able to deploy andrun arbitrary software, which can include operating systems andapplications. The consumer does not manage or control the underlyingcloud infrastructure but has control over operating systems, storage,deployed applications, and possibly limited control of select networkingcomponents (e.g., host firewalls).

Deployment Models are as follows:

Private cloud: the cloud infrastructure is operated solely for anorganization. It may be managed by the organization or a third party andmay exist on-premises or off-premises.

Community cloud: the cloud infrastructure is shared by severalorganizations and supports a specific community that has shared concerns(e.g., mission, security requirements, policy, and complianceconsiderations). It may be managed by the organizations or a third partyand may exist on-premises or off-premises.

Public cloud: the cloud infrastructure is made available to the generalpublic or a large industry group and is owned by an organization sellingcloud services.

Hybrid cloud: the cloud infrastructure is a composition of two or moreclouds (private, community, or public) that remain unique entities butare bound together by standardized or proprietary technology thatenables data and application portability (e.g., cloud bursting forloadbalancing between clouds).

A cloud computing environment is service oriented with a focus onstatelessness, low coupling, modularity, and semantic interoperability.At the heart of cloud computing is an infrastructure comprising anetwork of interconnected nodes.

Referring now to FIG. 7, a schematic of an example of a cloud computingnode is shown. Cloud computing node 6010 is only one example of asuitable cloud computing node and is not intended to suggest anylimitation as to the scope of use or functionality of embodiments of theinvention described herein. Regardless, cloud computing node 6010 iscapable of being implemented and/or performing any of the functionalityset forth hereinabove.

In cloud computing node 6010 there is a computer system/server 6012,which is operational with numerous other general purpose or specialpurpose computing system environments or configurations. Examples ofwell-known computing systems, environments, and/or configurations thatmay be suitable for use with computer system/server 6012 include, butare not limited to, personal computer systems, server computer systems,thin clients, thick clients, handheld or laptop devices, multiprocessorsystems, microprocessor-based systems, set top boxes, programmableconsumer electronics, network PCs, minicomputer systems, mainframecomputer systems, and distributed cloud computing environments thatinclude any of the above systems or devices, and the like.

Computer system/server 6012 may be described in the general context ofcomputer system executable instructions, such as program modules, beingexecuted by a computer system. Generally, program modules may includeroutines, programs, objects, components, logic, data structures, and soon that perform particular tasks or implement particular abstract datatypes. Computer system/server 6012 may be practiced in distributed cloudcomputing environments where tasks are performed by remote processingdevices that are linked through a communications network. In adistributed cloud computing environment, program modules may be locatedin both local and remote computer system storage media including memorystorage devices.

As shown in FIG. 7, computer system/server 6012 in cloud computing node6010 is shown in the form of a general-purpose computing device. Thecomponents of computer system/server 6012 may include, but are notlimited to, one or more processors or processing units 6016, a systemmemory 6028, and a bus 6018 that couples various system componentsincluding system memory 6028 to processor 6016.

Bus 6018 represents one or more of any of several types of busstructures, including a memory bus or memory controller, a peripheralbus, an accelerated graphics port, and a processor or local bus usingany of a variety of bus architectures. By way of example, and notlimitation, such architectures include Industry Standard Architecture(ISA) bus, Micro Channel Architecture (MCA) bus, Enhanced ISA (EISA)bus, Video Electronics Standards Association (VESA) local bus, andPeripheral Component Interconnect (PCI) bus.

Computer system/server 6012 typically includes a variety of computersystem readable media. Such media may be any available media that isaccessible by computer system/server 6012, and it includes both volatileand non-volatile media, removable and non-removable media.

System memory 6028 can include computer system readable media in theform of volatile memory, such as random access memory (RAM) 6030 and/orcache memory 6032. Computer system/server 6012 may further include otherremovable/non-removable, volatile/non-volatile computer system storagemedia. By way of example only, storage system 6034 can be provided forreading from and writing to a non-removable, non-volatile magnetic media(not shown and typically called a “hard drive”). Although not shown, amagnetic disk drive for reading from and writing to a removable,non-volatile magnetic disk (e.g., a “floppy disk”), and an optical diskdrive for reading from or writing to a removable, non-volatile opticaldisk such as a CD-ROM, DVD-ROM or other optical media can be provided.In such instances, each can be connected to bus 6018 by one or more datamedia interfaces. As will be further depicted and described below,memory 6028 may include at least one program product having a set (e.g.,at least one) of program modules that are configured to carry out thefunctions of embodiments of the invention.

Program/utility 6040, having a set (at least one) of program modules6042, may be stored in memory 6028 by way of example, and notlimitation, as well as an operating system, one or more applicationprograms, other program modules, and program data. Each of the operatingsystem, one or more application programs, other program modules, andprogram data or some combination thereof, may include an implementationof a networking environment. Program modules 6042 generally carry outthe functions and/or methodologies of embodiments of the invention asdescribed herein.

Computer system/server 6012 may also communicate with one or moreexternal devices 6014 such as a keyboard, a pointing device, a display6024, etc.; one or more devices that enable a user to interact withcomputer system/server 6012; and/or any devices (e.g., network card,modem, etc.) that enable computer system/server 6012 to communicate withone or more other computing devices. Such communication can occur viaInput/Output (I/O) interfaces 6022. Still yet, computer system/server6012 can communicate with one or more networks such as a local areanetwork (LAN), a general wide area network (WAN), and/or a publicnetwork (e.g., the Internet) via network adapter 6020. As depicted,network adapter 6020 communicates with the other components of computersystem/server 6012 via bus 6018. It should be understood that althoughnot shown, other hardware and/or software components could be used inconjunction with computer system/server 6012. Examples, include, but arenot limited to: microcode, device drivers, redundant processing units,external disk drive arrays, RAID systems, tape drives, and data archivalstorage systems, etc.

Referring now to FIG. 8, illustrative cloud computing environment 6050is depicted. As shown, cloud computing environment 6050 comprises one ormore cloud computing nodes 6010 with which local computing devices usedby cloud consumers, such as, for example, personal digital assistant(PDA) or cellular telephone 6054A, desktop computer 6054B, laptopcomputer 6054C, and/or automobile computer system 6054N may communicate.Nodes 6010 may communicate with one another. They may be grouped (notshown) physically or virtually, in one or more networks, such asPrivate, Community, Public, or Hybrid clouds as described hereinabove,or a combination thereof. This allows cloud computing environment 6050to offer infrastructure, platforms and/or software as services for whicha cloud consumer does not need to maintain resources on a localcomputing device. It is understood that the types of computing devices6054A-N shown in FIG. 8 are intended to be illustrative only and thatcomputing nodes 6010 and cloud computing environment 6050 cancommunicate with any type of computerized device over any type ofnetwork and/or network addressable connection (e.g., using a webbrowser).

Referring now to FIG. 9, a set of functional abstraction layers providedby cloud computing environment 6050 (FIG. 8) is shown. It should beunderstood in advance that the components, layers, and functions shownin FIG. 9 are intended to be illustrative only and embodiments of theinvention are not limited thereto. As depicted, the following layers andcorresponding functions are provided:

Hardware and software layer 6060 includes hardware and softwarecomponents. Examples of hardware components include mainframes, in oneexample IBM® zSeries® systems; RISC (Reduced Instruction Set Computer)architecture based servers, in one example IBM pSeries® systems; IBMxSeries® systems; IBM BladeCenter® systems; storage devices; networksand networking components. Examples of software components includenetwork application server software, in one example IBM WebSphere®application server software; and database software, in one example IBMDB2® database software. (IBM, zSeries, pSeries, xSeries, BladeCenter,WebSphere, and DB2 are trademarks of International Business MachinesCorporation registered in many jurisdictions worldwide).

Virtualization layer 6062 provides an abstraction layer from which thefollowing examples of virtual entities may be provided: virtual servers;virtual storage; virtual networks, including virtual private networks;virtual applications and operating systems; and virtual clients.

In one example, management layer 6064 may provide the functionsdescribed below. Resource provisioning provides dynamic procurement ofcomputing resources and other resources that are utilized to performtasks within the cloud computing environment. Metering and Pricingprovide cost tracking as resources are utilized within the cloudcomputing environment, and billing or invoicing for consumption of theseresources. In one example, these resources may comprise applicationsoftware licenses. Security provides identity verification for cloudconsumers and tasks, as well as protection for data and other resources.User portal provides access to the cloud computing environment forconsumers and system administrators. Service level management providescloud computing resource allocation and management such that requiredservice levels are met. Service Level Agreement (SLA) planning andfulfillment provide pre-arrangement for, and procurement of, cloudcomputing resources for which a future requirement is anticipated inaccordance with an SLA.

Workloads layer 6066 provides examples of functionality for which thecloud computing environment may be utilized. Examples of workloads andfunctions which may be provided from this layer include: mapping andnavigation; software development and lifecycle management; virtualclassroom education delivery; data analytics processing; and transactionprocessing.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a”, “an” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises” and/or “comprising”,when used in this specification, specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below, if any, areintended to include any structure, material, or act for performing thefunction in combination with other claimed elements as specificallyclaimed. The description of one or more embodiments has been presentedfor purposes of illustration and description, but is not intended to beexhaustive or limited to in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the art. Theembodiment was chosen and described in order to best explain variousaspects and the practical application, and to enable others of ordinaryskill in the art to understand various embodiments with variousmodifications as are suited to the particular use contemplated.

What is claimed is:
 1. A computer-implemented method of evaluatingfairness in devices under test, said computer-implemented methodcomprising: driving, by a plurality of drivers executing on one or moreprocessors of a computing environment, a plurality of commands on one ormore interfaces of a device under test, the plurality of commands totest the device under test in pre-silicon processing for fairness,wherein fairness indicates whether forward progress is being made forthe plurality of commands being driven on the one or more interfaces;checking state associated with the device under test, wherein the stateis based on status of selected commands driven by the plurality ofdrivers; determining, based on checking the state, whether the pluralityof drivers is to continue driving commands against the device undertest, wherein based on the determining indicating the plurality ofdrivers is to continue driving commands, deciding, based on a predefinedlimit, whether the test is to end; ending the test of the device undertest by stopping the driving of commands, based on deciding the test isto end, the ending the test providing an indication that the test hasfailed due to at least one fairness problem, in which forward progressis not being made for one or more commands being driven on at least oneinterface of the one or more interfaces, the at least one fairnessproblem to be addressed prior to post-silicon processing to improve adesign of the device under test; and correcting the at least onefairness problem pre-silicon, providing a design of an actual devicewithout the at least one fairness problem to be tested in post-siliconvalidation testing.
 2. The computer-implemented method of claim 1,wherein based on the determining indicating the plurality of drivers isto stop driving commands, stopping driving commands on the device undertest, the test of the device under test being successful.
 3. Thecomputer-implemented method of claim 2, wherein the stopping the drivingof commands comprises using a global quiesce point, the global quiescepoint indicating to the plurality of drivers that the driving ofcommands is to stop.
 4. The computer-implemented method of claim 3,wherein the selected commands comprise a command, for each driver of theplurality of drivers, executing the longest with reference to a selectedparameter, and wherein the global quiesce point is set based ondetermining that the command for each driver executing the longest hascompleted.
 5. The computer-implemented method of claim 1, wherein thechecking the state comprises checking whether the selected commands ofthe plurality of drivers have reached a predefined point in execution,and based on the checking indicating the selected commands have notreached the predefined point in execution, the determining indicates theplurality of drivers is to continue driving commands.
 6. Thecomputer-implemented method of claim 5, wherein the selected commandscomprise commands that have been executing the longest with reference toa selected parameter, and the predefined point in execution comprisescompletion.
 7. The computer-implemented method of claim 1, wherein theplurality of drivers comprises drivers of multiple types.
 8. Thecomputer-implemented method of claim 1, wherein the driving theplurality of commands comprises driving one or more commands by a driverof the plurality of drivers, wherein the driving the one or morecommands by the driver comprises: determining whether a pre-quiescelimit for the driver has been reached; continuing to drive commandsbased on the determining indicating the pre-quiesce limit has not beenreached; and taking a snapshot of a selected command driven by thedriver based on the determining indicating the pre-quiesce limit hasbeen reached, and continuing to drive commands on the device under test.9. The computer-implemented method of claim 8, wherein the selectedcommand includes a command driven by the driver that is executing thelongest with reference to a selected parameter, and taking the snapshotcomprises obtaining information regarding the command executing thelongest.
 10. The computer-implemented method of claim 9, wherein thechecking the state comprises checking whether the command of each driverof the plurality of drivers executing the longest has completed, andwherein the determining whether the plurality of drivers is to continuedriving commands comprises determining whether the plurality of drivershas indicated that their commands executing the longest have completed,wherein based on determining the plurality of drivers has indicated thattheir commands executing the longest have completed, setting a quiescepoint, the quiesce point indicating that the plurality of drivers is tostop driving commands, the quiesce point being set dynamically based onstatus of the commands executing the longest.
 11. A computer-implementedmethod of evaluating fairness in devices under test, saidcomputer-implemented method comprising: driving, by a plurality ofdrivers executing on one or more processors of a computing environment,a plurality of commands on one or more interfaces of a device under testto test the device under test in pre-silicon processing for fairness,wherein fairness indicates whether forward progress is being made forthe plurality of commands being driven on the one or more interfaces;checking state associated with the device under test; determining, basedon the state, whether a quiesce point is to be dynamically set for theplurality of drivers, the quiesce point to indicate to the plurality ofdrivers to stop driving commands against the device under test; setting,based on the determining indicating the quiesce point is to be set, thequiesce point dynamically, based on the state, to stop driving commandsagainst the device under test and successfully ending the test;deciding, based on the determining indicating the quiesce point is notto be set, whether commands are to continue to be driven, the decidingbeing based on a predefined limit, and wherein based on deciding thatthe commands are not to continue to be driven, failing the test due toat least one fairness problem in which forward progress in not beingmade for one or more commands being driven on at least one interface ofthe one or more interfaces, the at least one fairness problem to beaddressed prior to post-silicon processing to improve a design of thedevice under test; and correcting the at least one fairness problempre-silicon, providing a design of an actual device without the at leastone fairness problem to be tested in post-silicon validation testing.12. The computer-implemented method of claim 11, wherein the state isbased on status of selected commands driven by the plurality of drivers,and wherein the quiesce point is dynamically set based on the status ofthe selected commands.